Rotary casting method of killed steel

ABSTRACT

A rotary casting method for making a killed steel ingot wherein molten steel is charged into the ingot mold, the charged molten steel on its surface being sprayed with water or compressed cold air to form a coagulation layer, and after passage of a predetermined time period the ingot mold containing the molten steel is inverted or is positioned in horizontal direction, whereafter the inverted or horizontally directed ingot mold is returned to its original vertical upright position for coagulation of the molten steel.

'nite States Patent- 1 Saito et a1.

[ g ggldRY CASTING METHOD KILLED OTHER PUBLICATIONS [76] Inventors:Kimio Saito; Yutaka Fujisawa, both Making Shaping & Treating of SteelSteel 8th of 0/0 Itoh Iron & Steel Works Co., 1964 548449 Ltd., No. 4-1,5-chome, Matsue, Edogawa-ku, Tokyo, Japan Primary Examiner-Robert D.Baldwin [22] Filed: May 25 1971 Assistant ExaminerJohn E. Roethel [21]Appl. No.: 146,674

7 [57] ABSTRACT [52] US. Cl. 164/126, 164/136 A rotary Casting methodfor making a killed Steel ingot 2 g j B212d627/O8 wherein molten steelis charged into the ingot mold, 1 o earc 64/ l the charged molten steelon its surface being sprayed with water or compressed cold air to form acoagulation layer, and after passage of a predetermined time [56]References cued period the ingot mold containing the molten steel isUNITED STATES PATENTS inverted or is positioned in horizontal direction,448,881 3/1891 Hinsdale 164/122 whereafter the inverted or horizontallydirected ingot 3,364,978 1/1968 Tanoue et a] 164/114 mold is returned toits original vertical upright posi- 3,4l4,966 12/1968 Devin El 21] 64/114 UX tion for coagulation of the molten teel FOREIGN PATENTS ORAPPLICATIONS 5 C 3 D F 1,324,225 3/1963 France 164/114 "m I I alPAIENIEUJANZZW I 3.786.855

INVENTOR KIMIO SAITO YUTAKA FUJISAWA ATTORNEY l ROTARY CASTING METHOD OFKILLED STEEL BACK GROUND OF THE INVENTION BRIEF DESCRIPTION OF THEDRAWINGS In the drawings: FIG. 1 is a sectional elevation of the killedingot steel In casting methods heretofore practiced, the com- 5 cast inaccordance with the conventional method;

pletely deoxidized liquid steel has been charged into an ingot mold withthe formation of a globular shrinkage pipe having an oxidized surface atthe center of the steel ingot head, which therefore can not be weldedeven when subjected to the blooming mill and, as a result, must be cutoff with considerably low yield.

In this respect, improvement in yield by avoiding loss resulting fromthe severing of shrinkage pipe is an important consideration in the artof casting killed steel.

To increase the yield ingot molds have been specially designed withemphasis on charging conditions for the molten steel. It has also beenthe practice to provide a feeder head on the ingot mold in order togather the shrinkage pipe therein for subsequent cutting off of the saidfeeder head section after the rolling step. To initiate coagulation andto prevent oxidation within the pipe it has been the practice to pourwater on the ingot steel head.

In the known methods, however, the feeder head is eventually removed andthe undesirable oxidation nevertheless results.

SUMMARY OF THE INVENTION It is, accordingly, a general object of theinvention to obviate the above difficulties and disadvantages and toprovide a novel ingot casting method for making a killed steel withimproved yield.

In accordance with the present invention, the surface of the liquidsteel after being charged into the ingot mold is sprayed with water orwith compressed cold air to form a coagulation layer and with rotationof the ingot mold, the pipe resulting from shrinkage during coagulationis dispersed inthe forms of the small cavities at along the axis of theresulting ingot thereby preventing undersirable oxidation in the ingotsteel.

Another object of the present inventionis to provide a rotary castingmethod for making a killed steel which comprises charging the moltensteel into the ingot mold, spraying water or compressed cold air ontothe surface of the charged molten steel to form a coagulation layer,inverting the mold for of a predetermined time period the oralternatively rotating the mold containing the molten steel to behorizontally positioned, whereafter the inverted or horizontallypositioned ingot mold is rotated to its original vertical uprightposition for the completion of coagulation of the molten steel.

The ingot steel obtained by practice of the invention exhibits insection a homogeneous composition having disposed therein a shrinkagepipe in the form of small cavities along the longitudinal axis of theingot.

Other objects and advantages of the killed steel casting methodaccording to the invention will become apparent from a consideration ofthe following detailed description taken in conjunction with theaccompanying drawings wherein preferred embodiments of the invention areshown. However, it will be understood that the invention is not limitedto the details disclosed but includes all such variations andmodifications as fall within'the spirit of the invention and the scopeof the appended claims.

FIG. 2 is a sectional elevation of the killed ingot steel cast inaccordance with the present invention wherein the ingot steel afterbeing charged into the ingot mold is inverted 180; and

FIG. 3 is a sectional elevation of the killed ingot steel cast inaccordance with the present invention wherein the ingot steel afterbeing charged into the ingot mold is rotated 450 from an uprightvertical position to its illustrated horizontal positioned and thenreturned to its original vertical upright position.

DETAILED DESCRIPTION OF THE INVENTION:

The method of this invention will be further discussed hereinbelow inconjunction with the accompanying drawings.

In operation, the molten steel which has been completely deoxidized withdeoxidizers such as Si, Mn and the like by a known process is chargedinto the ingot mold. A few minutes after completion of the charging, theexposed surface in the ingot mold is sprayed with water or withcompressed cold air to form a coagulation layer thereon. The ingot moldis then reversed and thereafter returned to its original uprightvertical position for completing coagulation. Alternatively, the ingotmold after being charged with the molten steel rotated one revolutionplus (i.e. 450) and brought to rest in its horizontal position for 5-10seconds, whereafter its returned to its original upright verticalposition. The ingot mold may be sealed by a cover for prevention of thedisadvantageous oxidation and any unexpected accident such as anover-flow of the liquid steel.

The following non-limitative examples, in which all parts are expressedby weight, will serve to illustrate the practice of the invention inmore detail.

EXAMPLE 1 350 Kg of molten steel is poured into the ingot mold fordirect casting at an outlet temperature of 1,600C for a charging time of38 seconds and after 30 seconds pass, the exposed head surface haspoured thereon about 200 cc of water. After the 3 minutes 55 secondspass from the charging operation, the ingot mold is rotated 180, whichtakes 3 minutes, and returned into its original upright verticalposition for completion of coagulation.

EXAMPLE 2 350 Kg of molten steel is poured into the ingot mold fordirect casting at an outlet temperature of l,640C with a charging timeof 43 seconds and 30 seconds thereafter, the exposed head surface hasformed thereon about 200 cc of water. After elapse of 3 minutes 20seconds pass from the charging operation, the ingot mold is rotated oneand a quarter turns, i.e., rotated 450, which takes 3 minutes 30seconds, and maintained in a horizontal position for 6 seconds andsubsequently returned to its original upright vertical position for thecoagulation purpose.

Sectional views of steel ingot cast in accordance with the aboveExamples 1 and 2 are shown in FIGS. 2 and 3. As is apparent from thedrawings, no shrinkage pipe globules are formed at the head and bottomof the ingot. Instead only cavities of small size are dispersed somewhatnear the center axis. More particularly, a steel ingot cast according toExample 2, will exhibit colonies of cavities dispersed about the centeraxis, said cavities being completely isolated by the environmental chillcrystal zone forming the outer contour of the ingot, whereby undesirableoxidation is prevented.

In accordance with the'killed steel cast by the present invention, nooxidized layer is formed on the inner surface thereof despite thepresence of small pipe colonies dispersed therein. Moreover these pipesmay be eliminated by subjecting them to squeezing pressure during therolling operation without need therefore for cutting away sections as inprior art thereby increasing the yield considerably.

As a result of the fracture tests of the ingot steel cast in accordancewith the present invention by, for example, the S print test or themacroscopic corrosion test, no remarkable segregation could be seen andhence an ingot steel of homogeneous composition has resulted with animproved yield.

What we claim are:

1. A method of casting a steel ingot, which comprises charging moltensteel into a vertically arranged ingot mold, chilling the exposedsurface of the charged molten steel to form a coagulation layer,rotating the ingot mold through at least about a horizontal axis duringa time sufficient to disperse the resulting shrinkage pipe in the formof small cavities along the axis of the resulting ingot, maintaining theingot mold in its rotated position for a time sufficient to stabilizethe resulting small-cavity pipe dispersion, and thereafter returning theingot mold to a vertical position.

2. A method according to claim 1, wherein the ingot mold after beingcharged with molten steel is rotated 180 for a predetermined time,whereafter the ingot mold is rotated to its original vertical position.

3. A method according to claim 1, wherein the ingot mold after beingcharged with molten steel is rotated 450 from its upright verticalposition for a predetermined period for disposition in a horizontaldirection, maintaining the ingot mold in said horizontal direction for apredetermined time, and returning, after said lapse of saidpredetermined time, said ingot mold to its original position.

4. A method according to claim 3, wherein said ingot mold is maintainedin said horizontal position for between 5 to 10 seconds.

5. A method according to claim 3, wherein said ingot mold is maintainedin said horizontal direction for 6

1. A method of casting a steel ingot, which comprises charging moltensteel into a vertically arranged ingot mold, chilling the exposedsurface of the charged molten steel to form a coagulation layer,rotating the ingot mold through at least 180* about a horizontal axisduring a time sufficient to disperse the resulting shrinkage pipe in theform of small cavities along the axis of the resulting ingot,maintaining the ingot mold in its rotated position for a time sufficientto stabilize the resulting small-cavity pipe dispersion, and thereafterreturning the ingot mold to a vertical position.
 2. A method accordingto claim 1, wherein the ingot mold after being charged with molten steelis rotated 180* for a predetermined time, whereafter the ingot mold isrotated to its original vertical position.
 3. A method according toclaim 1, wherein the ingot mold after being charged with molten steel isrotated 450* from its upright vertical position for a predeterminedperiod for disposition in a horizontal direction, maintaining the ingotmold in said horizontal direction for a predetermined time, andreturning, after said lapse of said predetermined time, said ingot moldto its original position.
 4. A method according to claim 3, wherein saidingot mold is maintained in said horizontal position for between 5 to 10seconds.
 5. A method according to claim 3, wherein said ingot mold ismaintained in said horizontal direction for 6 seconds.